This invention relates to shipping crates for chemicals such as tetraethylorthosilicate ("TEOS") which is used in integrated circuit fabrication.
In the semiconductor industry, a variety of chemicals are employed during the fabrication of integrated circuits. For example, TEOS is widely used as a feed stock to a plasma enhanced reactor which forms silicon dioxide layers. Such chemicals are often shipped in bulk delivery tanks, including 200 liter canisters. When filled, these tanks can be quite heavy and may weigh 600 pounds or more. As a result, forklifts have previously been used to move filled tanks, including use of forklifts to place a filled canister in a storage and delivery cabinet. However, use of a forklift is prone to difficulties, such as potential rupture of the vessel, difficulty of loading tanks in narrow walkways, lack of access in cleanrooms, and so forth.
In addition, the tanks have been housed in delivery cabinets. The delivery cabinets include hardware attached to the tanks for withdrawing chemicals from the tanks and sending the withdrawn chemicals to a delivery point, typically a smaller delivery canister. Prior cabinets functioned as containment vessels. The cabinets have heretofore been oversized so that a spill may collect in the bottom of the cabinet. For instance, a grating is typically installed to act as a false floor, with the tank resting on the grating. The grating permits liquid spills to run into the reservoir in the bottom of the cabinet. A chemical spill in a conventional cabinet is, however, problematic for several reasons. For instance, the cabinet itself must be taken off line so that it can be cleaned. As a result, supply of chemical from the contaminated cabinet is foreclosed during clean-up. Such down time of the supply cabinet may result in temporary shut down of the process equipment utilizing the cabinet for chemical supply. For large, bulk cabinets, up to 30 systems could be potentially be down, which would be very costly event during integrated circuit fabrication.
Furthermore, because the cabinet is oversized as protection in the event of a spill, the cabinets may take up more space than would otherwise be desirable. Space is valuable in any fabrication operation. Hence, a system which enables containment of spills but which has a smaller size would be highly desirable. Likewise, since prior bulk cabinets included the aforementioned grating, the bulk tanks needed to be lifted for placement in the cabinet.